An FBI study of 160 “active shooter” incidents between 2000 and 2013 found that only 6 incidents, or 3.8%, were perpetrated by a female shooter. All six of these female shooters used handguns, according to the FBI study. The deadliest of these shootings, at a post office in Santa Barbara, California, in 2006, left six victims dead. Five of the six incidents involved women opening fire on current or former coworkers at their workplaces, including at the University of Alabama, a supermarket in Florida, and a factory in Philadelphia, all in 2010.

A different count of public mass shootings, one based on the number of fatalities, rather than the behavior of the shooter, includes only two incidents with a lone female perpetrator.

Overall, men are much more likely to commit murders than women are, according to FBI data. When it comes to domestic gun violence in America, women are also much more likely to be the victims of fatal domestic shootings than men are, according to a 2016 investigation by the Associated Press.

At least 760 Americans were killed with guns each year by spouses, ex-spouses or dating partners between 2006 and 2016, according to an in-depth analysis of homicide data from Florida and the FBI. But men were much less likely to be shot to death by romantic partners than women were. Overall, women were the victims in more than four out of every five of these incidents, the Associated Press found.

Mother Jones’ mass shooting database also includes one shooting, the 2014 San Bernardino attack, with a joint male and female perpetrator. Married couple Syed Farook and Tashfeen Malik opened fire on a holiday party of Farook’s co-workers in 2014 with military-style rifles, leaving 14 people dead.

There are multiple competing definitions of what counts as a “mass shooting” in America, where incidents of public mass violence are common, and it’s not clear if the YouTube shooting meets any of these definitions. The nonprofit Gun Violence Archive, which tracks incidents of gun violence using media reports, defines a mass shootings numerically as any incident in which at least four people are shot, not including the perpetrator, regardless of whether any of the victims are killed.

Mother Jones tracks public mass shootings between 1982 and 2012 with at least four victims shot and killed. Starting in 2013, Mother Jones lowered this threshold to at least three victims shot and killed, citing a mandate from President Obama. The Mother Jones mass shootings database excludes public acts of gang violence or shootings linked to robberies or other crimes, aiming to focus on shooters who attack large numbers of people at schools, movie theaters, or other public venues.